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Lavry AD122-96 Mark III Operation Manual

96khz mastering quality analog to digital converter
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Model AD122-96
Mark III
96kHz Mastering Quality Analog to Digital
Converter
Operations Manual
Lavry Engineering, Inc.
945 Hildebrand Lane NE
Suite 110
Bainbridge Island, WA
98110
(206) 842-3552
http://www.lavryengineering.com/
email: techsupport@lavryengineering.com
Revision 1.2
March 2005

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Summary of Contents for Lavry AD122-96 Mark III

  • Page 1 Model AD122-96 Mark III 96kHz Mastering Quality Analog to Digital Converter Operations Manual Lavry Engineering, Inc. 945 Hildebrand Lane NE Suite 110 Bainbridge Island, WA 98110 (206) 842-3552 http://www.lavryengineering.com/ email: techsupport@lavryengineering.com Revision 1.2 March 2005...
  • Page 2 “the accountability” of lower and higher audio frequencies, Model AD122 provided a 122dB with no A weighing. The second generation converter, The AD122-96 provided was an extension from the standard 44.1-48KHz sampling rate to “double speed” (88.2 and 96KHz sampling). The double speed range dynamic range was lower then the standard range, and it was upgraded to the AD122 MKII.

  • Page 3: Limited Warranty

    Subject to the conditions set forth below, for one year after the original purchase date of the product, Lavry Engineering will repair the product free of charge in the United States in the event of a defect in materials or workmanship.

  • Page 4: Table Of Contents

    Specifications..................12 Appendix I Acoustic Bit Correction™ ..............13 Noise-Shaping Curves ............... 16 Appendix II AD122-96 MKIII Input Considerations ..........17 Appendix III AD122-96 MKIII Soft Saturation ............. 19 Appendix IV Viewing Noise Floor on AD122-96 MKIII Display ......21...

  • Page 5: Part I Introduction

    96 kHz narrow lock range, 88/44 kHz, or 96/48 kHz. Vernier Transfer Function Correction™: The exceptional performance of Lavry Engineering’s AD122-96 MKIII is due to design innovations in both analog and digital sections. The high power consumption of the A/D modules, using high voltage rails and high current, enables the use of discrete large geometry components.

  • Page 6: Operating Instructions

    AD122-96 MKIII Operating Instructions Operation of the Model AD122-96 MKIII Mastering Quality Analog to Digital Converter requires the use of five push button switches located on the front panel. The liquid crystal display is organized for a quick and intuitive operator interface. The unit features six screen displays.

  • Page 7: Main Screen

    AD122-96 MKIII Operations Manual Main Screen The main screen is used for selecting the A to D clock source and output word length parameters. The top line controls the A to D clock source: 44.1kHz INTERNAL CRYSTAL 20 BITS WL ABC: FLAT NSOFF When setting for internal clock operation, choose sample rate and internal crystal mode: 44.1kHz INTERNAL CRYSTAL...

  • Page 8: Word Length And Acoustic Bit Correction

    Operations Manual AD122-96 MKIII Word Length and Acoustic Bit Correction The bottom line controls word length and Acoustic Bit Correction™ parameters: 44.1kHz INTERNAL CRYSTAL 20 BIT WL ABC: HPDF Setting Word Length: The selection of word length (16 to 24 bits) sets the digital output word length. The NI setting (word length not indicated) is a 20 bits default setting as per AES/EBU specifications.

  • Page 9: Audio Control Screen

    The feature emulates magnetic tape saturation. DC offset removal: The Model AD122-96 MKIII converts signals down to DC (0Hz). The total DC offset (due to DC offset within the audio signal and the offset of the converter itself) can be removed. Removing the offset sets the lower line to DC REMOVAL ON.

  • Page 10: Bar Graph & Display Screen

    Data limiting settings: The symbol 0 (low) on the top line, “FINE:OFF 20 METER: -00 0” indicates that the AD122-96 MKIII passes full-scale values unchanged. The symbol 1 indicates that full-scale values are limited to 1 least-significant bit less than full scale. In this mode downstream machines will not show overs.

  • Page 11: Warm-Up And Calibration

    AD122-96 MKIII Operations Manual any of the front panel switches. When PEAK/HOLD is OFF, the MAX lamp will flicker when a single full-scale sample is encountered. Display contrast: The LCD display may be adjusted from 0 to 7. Warm-up and Calibration The recommended warm up time is 15 minutes.

  • Page 12: Hardware Interconnections

    Maintenance The Model AD122-96 MKIII is an auto calibrating converter requiring no periodic adjustments. The unit's reliance on linear power supplies and discreet class A analog circuitry generates significant amount of heat (25 watts maximum). The temperature rise is no cause for concern, but allowing for some airflow is always a benefit from a long-term reliability standpoint.

  • Page 13: Part Ii Specifications

    AD122-96 MKIII Operations Manual Specifications Part II: Analog Inputs: The analog signal can be amplified by 0-12dB utilizing the front panel screw adjust trim pots. Full- scale signal with 0dB gain is 24dBu, (full-scale signal with 12dB gain is 12dBu).

  • Page 14: Acoustic Bit Correction

    The Model AD122-96 MKIII offers High Pass or Flat Dither type and four noise-shaping curves. Model AD122-96 MKIII allows the user to use dither with or without noise shaping. Operating noise shapers without dither is undesirable so the unit automatically shuts the noise shaper off when dither is off.
  • Page 15 (8-12 bits) should be avoided. The ideal noise-shaping curve may be irritating at loud levels. Lavry Engineering’s listening tests were based on test tones and repeating loops of quiet passages of various material (mostly classical music) with flat amplifier response. Listening to test tones was straightforward: we used the Model AD122-96 MKIII test tone generator mode switching the Acoustic Bit Correction™...
  • Page 16 Operations Manual AD122-96 MKIII Figure 6 shows the effect of high-pass triangular dither only. The more coherent data in the dithered bits, the better the dithering process works. Note that dithering from 24 bits to 22 bits has a lower noise floor but more visible distortion components than dithering to a shorter word length, due to fewer bits in the portion of the word being truncated.

  • Page 17: Noise-Shaping Curves

    AD122-96 MKIII Operations Manual Noise-Shaping Curves Figure 11 compares Flat dither AUDIO PRECISION FFT AMP1(dBFS) FREQ(Hz) 26 JUN 94 14:42:15 -80.00 with NS2, NS3, and NS4 noise- -85.00 -90.00 shaping curves. Note the -95.00 increasing aggressiveness of the -100.0 -105.0 curves, with the pronounced dip -110.0...

  • Page 18: Ad122-96 Mkiii Input Considerations

    AD122-96 MKIII Input Range: You may suspect by now that our aim is to provide you with an A/D converter and leave the problem of providing a "hot" signal at the hands of microphone and mic- preamplifier manufacturers.
  • Page 19 AD122-96 MKIII Operations Manual Note: Much information is available regarding proper shielding. The well known book "Grounding And Shielding in Instrumentation" by Ralph Morrison provides an excellent explanation of the subject and points out clearly that the floating shield connection is the correct configuration. Engineers using the grounded configuration with 16-17 bit systems may wish to re-evaluate their interconnections for 20 bit systems.

  • Page 20: Ad122-96 Mkiii Soft Saturation

    Operations Manual AD122-96 MKIII Appendix III: AD122-96 MKIII Soft Saturation The SOFT SATURATION feature provides a digital emulation of an ideal magnetic tape saturation characteristic. The three available settings are: 1. SOFT SATURATION OFF: yields normal converter operation (see lower curve VOFF).
  • Page 21 AD122-96 MKIII Operations Manual Below are time domain plots for the +3dB setting (left plot) and +6dB setting (right plot). Each plot shows the transformation of two input signals (dotted lines) to two output signals (solid lines). The settings provide different tradeoffs between gain and "peak signal distortion".

  • Page 22: Viewing Noise Floor On Ad122-96 Mkiii Display

    Gaussian noise energy is measurable via a rms. (root mean square) meter. The proper measurement of converter noise should be done using a rms. instrument (such as Lavry Engineering’s Model 3000, Audio Precision test system or others). However, the known bell shaped curve coupled with a peak reading offers a reasonable and quick estimate of the rms.
  • Page 23 AD122-96 MKIII Operations Manual Such measurement and calculation may aid in evaluating the noise of a driver device, or a series of devices. The distribution due to addition of Gaussian signals is still Gaussian. While the 8dB "translation factor" is true for Gaussian noise, it does not hold true for non-Gaussian noise. Such factor is 3dB for sine waves and 0dB for square waves.

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